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article imageT. rex and cousins had uniquely serrated teeth, scientists find

By Megan Hamilton     Jul 29, 2015 in Science
For some time, scientists have known that Tyrannosaurus rex and other theropod dinosaurs had serrated teeth.
They knew that those teeth, with their jagged edges worked like steak knives to help their owner tear through flesh.
New research has added another dimension to this story.
A few years ago, scientists discovered that theropod dinosaurs had some rather unusual structures inside their teeth — a maze of interconnected cracks and voids that many attributed to wear and tear from crunching down on bones, The Los Angeles Times reports.
However, research published Tuesday in the journal Scientific Reports, provides another explanation regarding the function of these structures. It turns out that they were present in the teeth while they were still deep inside the dinosaur's gums, and they played a crucial role in maintaining that knife-like serrated edge that the teeth of these huge predators are known for.
Theropod dinosaurs were some of the largest terrestrial predators that Earth has ever known, NBC News reports. Appearing about 200 million years ago, they were the dominant meat-eaters until the end of the age of dinosaurs about 65 million years ago.
The study involved eight theropod species and it showed that these internal structures were arranged in a way that strengthened and prolonged the life of the teeth.
Kirsten Brink, a postdoctoral researcher at the University of Toronto and the study's first author says the evidence shows that T. rex's teeth could indeed crush bone. The teeth of this huge predator have been found embedded in the bones of its prey and chunks of bone appear in its coprolites, or fossilized dung, NBC reports.
"All animal teeth are made from the same building blocks, but the way the blocks fit together to form the structure of the tooth greatly affects how that animal processes food," Brink said in a statement. "The hidden complexity of the tooth structure in theropods suggests that they were more efficient at handling prey than previously thought, likely contributing to their success."
The researchers studied a tiny feature that looked like a crack at the bottom of the serrations — a feature that can only be seen when the tooth is cut open. This feature isn't something seen in other animals with serrated teeth, and a previous study suggested that the cracks were formed by use, The Washington Post reports. In effect, it was suggested that they were stress cracks that formed when the dinosaurs crunched hard bone, and their formation prevented the tooth from shattering.
However, this new study suggests that these "cracks" were there to begin with. The researchers studied teeth that hadn't erupted yet (dinosaurs, like sharks, shed and produced teeth continuously throughout their lives), along with teeth that had been used for eating. That's when they found evidence that these odd structures at the bottom of the serrations were there from the start.
The scientists were able to determine this by using a powerful scanning electron microscope, along with a synchroton and spectroscope (devices that aid in analyzing chemical composition) as part of the experiment. Brink and her co-authors examined thin tooth slices from the eight carnivorous theropods (including T. rex) and from other animals with serrated teeth--including an extinct shark and a Komodo dragon, The Los Angeles Times reports.
Studying the erupted and unerupted teeth, the scientists found that the internal structure was found only in the theropods.
"The strange structure is actually a special arrangement of tooth tissues that increases the size of the serration, strengthening it and preventing it from wearing away quickly," Brink told the Post. "This means that teeth could last longer in the jaw, preventing gaps from occurring in the tooth row while a new tooth is developing, allowing for a more efficient bite when piercing through the flesh of its meal."
Tyrannosaurus rex is easily one of the largest meat-eating dinosaurs that has ever lived, National Geographic reports. With jaws that were four feet long, T. rex was an expert at crushing bone.
At about 40 feet long and standing 15 to 20 feet high, T. rex had strong thighs and a tail that was long and powerful, meaning that it could move quickly.
This massive creature could rip off 500 pounds of meat in one bite, scientists think. T. rex fossils have been found with Triceratops and Edmontosaurus, and this suggests T. rex likely crushed and broke bones as it ate, National Geographic reports.
More about Dinosaurs, t rex, Tyrannosaurus rex, serrated teeth, unusual structures
 
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